Now I got error after adding those lines mentioned above

Status: 500 Content-type: text/html

Software error:

Global symbol "$buffer" requires explicit package name at chktr.pl line 22.
Global symbol "$buffer" requires explicit package name at chktr.pl line 25.
Global symbol "@pairs" requires explicit package name at chktr.pl line 32.
Global symbol "$buffer" requires explicit package name at chktr.pl line 32.
Global symbol "$pair" requires explicit package name at chktr.pl line 33.
Global symbol "@pairs" requires explicit package name at chktr.pl line 33.
Global symbol "$name" requires explicit package name at chktr.pl line 34.
Global symbol "$value" requires explicit package name at chktr.pl line 34.
Global symbol "$pair" requires explicit package name at chktr.pl line 34.
Global symbol "$value" requires explicit package name at chktr.pl line 35.
Global symbol "$value" requires explicit package name at chktr.pl line 36.
Global symbol "$value" requires explicit package name at chktr.pl line 37.
Global symbol "$name" requires explicit package name at chktr.pl line 38.
Global symbol "$value" requires explicit package name at chktr.pl line 38.
Global symbol "$url" requires explicit package name at chktr.pl line 41.
Global symbol "$end" requires explicit package name at chktr.pl line 42.
Global symbol "$begin" requires explicit package name at chktr.pl line 43.
Global symbol "$end" requires explicit package name at chktr.pl line 43.
Global symbol "$dir" requires explicit package name at chktr.pl line 44.
Global symbol "$lin" requires explicit package name at chktr.pl line 45.
Global symbol "$dir" requires explicit package name at chktr.pl line 48.
Global symbol "$dir" requires explicit package name at chktr.pl line 48.
Global symbol "@files" requires explicit package name at chktr.pl line 49.
Global symbol "$f" requires explicit package name at chktr.pl line 52.
Global symbol "@files" requires explicit package name at chktr.pl line 52.
Global symbol "$f" requires explicit package name at chktr.pl line 53.
Global symbol "$f" requires explicit package name at chktr.pl line 53.
Global symbol "$f" requires explicit package name at chktr.pl line 54.
Global symbol "$f" requires explicit package name at chktr.pl line 54.
Global symbol "$dir" requires explicit package name at chktr.pl line 55.
Global symbol "$f" requires explicit package name at chktr.pl line 55.
Global symbol "$begin" requires explicit package name at chktr.pl line 55.
Global symbol "$end" requires explicit package name at chktr.pl line 55.
Global symbol "@f" requires explicit package name at chktr.pl line 56.
Global symbol "$i" requires explicit package name at chktr.pl line 57.
Global symbol "@f" requires explicit package name at chktr.pl line 60.
Global symbol "@f" requires explicit package name at chktr.pl line 61.
Global symbol "$i" requires explicit package name at chktr.pl line 62.
Global symbol "$lsiz1" requires explicit package name at chktr.pl line 63.
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